Forming of flexible drinking straws



Aug. 29, 1967 w. NARDONE FORMING OF FLEXIBLE DRINKING STRAWS Filed March 16. 1966 United States Patent 3,339,004 FORMING 0F FLEXIBLE DRINKING STRAWS William Nardone, Revere, Mass, assignor to Sweetheart Plastics, Inc., Wilmington, Mass. Filed Mar. 16, 1966, Ser. No. 542,984 7 Claims. (Cl. 264-293) This application is a continuation-in-part of co-pending US. patent application Ser. No. 501,604, filed Oct. 22, 1965, now abandoned.

This invention relates to the manufacture of flexible drinking straws and more particularly comprises a new and improved method for crimping or pleating straws to form a flexible section intermediate the ends.

One important object of this invention is to provide a simple and inexpensive method for pleating straws over a portion of their length so as to render them flexible.

Another important object of this invention is to provide a method for pleating or crimping straws which may be carried out at high speed.

Another important object of this invention is to provide a method for crimping straws made of plastic, which may be carried out without the use of special forming dies and without heating or otherwise rendering workable the material from which the straw is made.

Still another important object of this invention is to provide a method for pleating plastic straws, which will cause the straws to maintain their pleated configuration after treatment rather than return to their original shape under the influence of the memory of the material.

To accomplish these and other objects the method and apparatus of this invention includes a pair of rods which may be inserted within the straw from opposite ends. The rods are inserted in the straw so that their adjacent ends within the straw are separated a distance substantially equal to the length of the portion of the straw which is to be pleated. After the rods are inserted in position, clamping devices engage the outer surfaces of the straws at the adjacent ends of the rods and grip the straws so that the gripped portions may. not move relative to the separate rods surrounded by them. Subsequently, the rods are moved rapidly toward one another with the clamps causing the portion of the straw which lies between the ends of the rods to collapse and form pleats. Thereafter, the rods are removed from the pleated straw.

These and other objects and features of the present invention will be better understood and appreciated from the following detailed description of one'embodiment thereof, selected for purposes of illustrating and shown in the accompanying drawing, in which:

FIG. 1 is a greatly enlarged side view of the apparatus in diagrammatic form used to pleat the intermediate portion ofa straw, shown in its condition before the actual pleating occurs;

FIG. 2 is a view similar to that of FIG. 1 but shows the apparatus in the position assumed immediately following the pleating operation;

FIG. 3 is a cross-sectional view taken along the corresponding section line in FIG. 1;

FIG. 4 is a side view of a straw manufactured in accordance with the illustrations of FIGS. 1 and 2; and

FIGS. 5 and 6 are cross-sectional views taken along the section lines 55 and 6-6 of FIG. 4;

In FIG. 1 a straw 10 having a smooth unpleated and uncorrugated cylindrical side wall 12 and open ends 14.

and 16 is shown mounted over a pair of rods 18 and 20. Each of the rods 18 and 20 have a generally smooth outer surface 22 and 24, respectively, and generally conform to the side of the inner diameter of the cylindrical wall 12 of the straw. However, in order to prevent the creation of a vacuum between the ends of therods,

3,3 9,004 Patented Aug. 29, 1967 ice;

or make it difiicult to insert the rods, by creating a pressure chamber between their ends, the rods are slightly less in diameter than the inner diameter of'the straw so that air will be allowed to bleed into and out of the space between the rod ends.

The rod 18 is provided with an integral collar or stop 26 which bears against the end 14 of the straw to control the depth of insertion of the rod into that end of the straw. The inner end 28 of the rod is provided with a cylindrical recess 30 that receives a guide pin 32 connected to the inner end 34 of the other rod 20. In FIG. 1 the end 34 of the rod 20 is shown spaced from the end 28 of the rod 18 so that the central portion 36 of the straw 10 is unsupported. The central portion 36 disposed between the ends of the rods is, in accordance -with this invention, pleated to become a flexible section in the straw.

A pair of split clamps 38 and 40' surround the ends 28 and 34, respectively, of the two rods, and each clamp is composed of two semicircular parts so that the clamps may be opened. In FIG. 3, the two parts of clamp 38 are identified as 38a and 38b. The clamps are designed to grip firmly the portion of the straw surrounded by each onto the portion of the rod in turn surrounded by the respective portions of the straw, so that each end of the straw is not permitted to move relative to the rod which it surrounds. That is, the clamp 38 when operative prevents the portion 42 of the straw 10 from moving with respect to the rod 18, and the clamp 40 when operative prevents the portion 44 of the straw from moving relative to the rod 20. The semi-circular sections of each clamp are urged toward one another by a spring 46 connected between a pair of posts 48 in turn firmly anchored to the respective clamping members. The sections of the clamp are moved against the bias of the spring 46 under the influence of actuators 50 so as to separate the clamps and allow the straws to be removed from the rods.

The actuators 50 may take any one of several forms. Typically, they may be pneumatic cylinders operated from a compressed air source. Alternatively, they may be electrically operated and take the form of solenoids which act against the direction of pull of spring 46 when each is actuated. The particular form taken by the actuators is not critical to the invention.

7 After the straw is mounted in the position shown in FIG. 1 to that shown in FIG. 2. It will be noted in that figure that the ends 28 and 34 of the rods 18 and 20, respectively, are spaced closely with respect to "one another (for purposes of clarity, the spacing is exaggerated). Thereafter, the clamps 38 and 40 are released by the actuators 50 and the rods separated so as to allow the straw to be removed.

7 When the clamps are released and the straw is allowed to move with respect to the rods, the pleats formed in the mid-section 36 open somewhat and the straw assumes the configuration shown in FIGS. 4-6. In those figures it will be noted that a plurality of rows of substantially diamond-shaped pleats are formed circumferentially about the portion 36 of the straw, and the pleats of each row are displaced with respect to the adjacent rows. Thus, the top row. 51 of pleats 52, shown at the right in FIG. 4, is disposed immediately adjacent a second row 54 composed of identical pleats 52 but which are displaced with respect to the pleats in the top row 51. Each pleat is composed of a central hinge fold 56 between a pair of substantially isosceles triangle-shaped leafs 58 with the 3 unequal side of two adjacent pleats being joined at the hinge fold 56. The outer edges 60 of each leaf define or correspond to the outer edges of the leafs of the adjacent pleats of adjacent rows. This straw is defined in detail in my co-pendingapplication Ser. No. 501,605 filed Oct. 22, 1965, now abandoned.

The rods 18 and 20, the clamps 38 and 40 and the movement of the straw onto the rods may be automated in several different ways. For example, the rods may be cam actuated to cause them to move back and forth axially toward one another, or one rod may be stationary while the other is movable, and the movable rod may be actuated either electrically, hydraulically, pneumatically or mechanically. For example, a straw may be carried by brushes onto one of the rods which in turn then moves toward the other of the rods, causing the second rod to slide into the free end of the straw. Thereafter, the rod or rods may be actuated toward each other to perform the pleating operation. After the rods are separated and the clamps released a brush may sweep the straw from the rod upon which it is carried.

In accordance with the method of this invention the straw is mounted over the end of one of the rods with the end of that rod lying within the straw. And the rod and straw are moved relative to the other rod so that the other rod lies within the other end of the straw. Next, the clamps engage the straw adjacent the end of each rod, and thereafter the rods are moved toward one another so as to pleat the portion of the straw between the adjacent ends of the rod. The formation of pleats can be carried out without the need for pleating dies. The pleating operation may be more uniform if the straw is scored or creased at one spot adjacent the end of either rod. For example, a slight nick or crease may be made in the straw portion 36 adjacent the end 34 of rod 20 by a knife or other tool just before the rod 20 is moved toward the other rod, which will start the first pleat formation. Then the clamps are released and the rods are removed.

In a specific embodiment of this invention a circular cross-section straw made of polypropylene having a melt index of 3.5 (ASTM) and having an inside diameter of 0.24 inch and a wall thickness of 0.0045" is pleated in accordance with the preferred method of this invention. The straw 10 is placed in the apparatus shownin FIG. 1 with ends 28 and 34 being approximately 0.9 inch apart. Pin 32 has a diameter of 0.183 inch. Rod along with the portion held by clamp is subjected to substantially instantaneously applied force moving it approximately 0.6 inch toward rod 18 into the position shown in FIG. 2 after which the clamps 38 and 40 are released and the pleated straw removed from the apparatus. The method is carried out at standard room temperature of 20 C. The resultant straw has a length of 7.925 inches as compared with its starting length of 8.5 inches. Fourteen creases or pleats are formed in a section having an axial length of about 0.325 inch and the straw has the configuration illustrated in FIGS. 4-6. The widest inside diameter of the pleated section occurs between each of the opposed points 70, and as illustrated at A is approximately 0.25 inc-h; the distance B from each point 70 to the next adjacent point 70 shown is approximately .07 inch and each radial distance C is approximately 0.05 inch.

When successive straws are processed using the method and values of the preferred embodiment substantially similar results are obtained. It should be understood that the drawing illustrates perfectly formed geometric patterns in the creased section. However, in some cases the pattern can be slightly irregular and the crease lines are gently rounded as at 65, 60 and 56.

The straws of the speific embodiment can easily be flexed at an angle of at least 50 to their original axis. While a specific embodiment of this invention has been shown and described, it will be apparent from the foregoing description that numerous modifications may be made without departing from the spirit of the invention.

For example, the straws pleated can be of any material which will not fracture during the pleating operation. Such materials include but are not limited to polyethylene, polybutene, nylon and impact polystyrene.- The specific configuration shown in FIGS. 4-6 can be varied with modified operation of the method to give irregular and varying configuration pleats. The inner fold lines indicated at 65 need not be straight. Thus, if the diameter of guide pin 32 is enlarged to touch the pleat lines during the step shown in FIG. 2, arcuate lines 65 may result. Similarly, if the guide pin is non-circular in cross-section, varying configurations in lines 65 can be obtained. The number and size of the pleats can vary depending on the dimensions of the original straw. In all cases, a suificient number of pleats are provided to permit desired bending of the straw. A minimum of at least three pleats is preferred. Non-circular, oval, or polygonal cross-sectioned straws can be pleated in the method of this invention by the use of corresponding rods designed to support ends of such straws as described above. In some cases, either or both of rods 18 and 20 can be tubes and a slip tube arrrangement used. While the method is preferably carried out at standard room temperature, higher or lower temperatures can be used depending on the nature of the plastic processed. Therefore, it is not intended to limit the scope of this invention to the specific embodiment illustrated and described. Rather, it is intended that the scope of this invention be determined by the appended claims and their equivalents.

What is claimed is: 1. A method of making flexible plastic straws comprising the steps of inserting a straw over the ends of a pair of rods which are aligned end to end, creasing the straw over a portion of its circumference adjacent the end of one rod, and moving the rods toward one another and holding the straw immovable with respect to each rod over that portion surrounding each of said rods causing the straw to pleat between the ends of the rods. 2. A method of making flexible plastic straws comprising the steps of mounting a straw over a pair of rods which are aligned axially and with their ends spaced apart, gripping the portion of the straw surrounding each rod so that the rods may not move relative to their respective surrounding portions, and moving the rods toward one another while the gripping step continues causing the straw to pleat over a portion of its length substantially equal to the distance that separates the rods. 3. A method of making flexible plastic straws comprising the steps of providing a plastic seamless straw and a pair of aligned rods of diameter smaller than the diameter of said straw, mounting the straw over the end of one of said rods with the end of that rod lying within the straw, moving the straw and said one rod relative to the other rod toward each other so that the other rod lies within the straw, gripping the portions of the straw surrounding the two rods so that those portions do not move relative to the two rods, moving the two rods further toward one another causing the portion of the straw lying between the ends to pleat, and thereafter removing the straw from the rods. 4. A method as defined in claim 3 further characterized by the'step of scoring the straw at the region of the end of one of said rods prior to the step of moving the two rods further toward each other.

5. A method as defined in claim 3 further characterized by 5 the step of separating the rods a distance exceeding the length of the straw after pleating and before the straw is removed from the two rods. 6. A method of making flexible plastic straws comprising,

supporting two end portions of an elongated axially extending plastic straw with an unsupported intermediate portion therebetween, and moving said end portions axially inwardly with respect to each other to form a plurality of pleats in said intermediate portion. 7. A method in accordance with the method of claim 6 wherein said two end portions are internally supported prior to said moving step.

6 References Cited UNITED STATES PATENTS 3/1953 Freidman 264-294 7/1955 Holte 264-320 XR 5/1958 Tapp.

12/1961 Zeig 264-286 XR 3/1966 La-rkin 264-286 XR FOREIGN PATENTS 7/1962 Canada.

ROBERT E. WHITE, Primary Examiner.

R. R. KUCIA, Assistant Examiner. 

1. A METHOD OF MAKING FLEXIBLE PLASTIC STRAWS COMPRISING THE STEPS OF INSERTING A STRAW OVER THE ENDS OF A PAIR OF RODS WHICH ARE ALIGNED END TO END, CREASING THE STRAW OVER A PORTION OF ITS CIRCUMFERENCE ADJACENT THE END OF ONE ROD, AND MOVING THE RODS TOWARD ONE ANOTHER AND HOLDING THE STRAW IMMOVABLE WITH RESPECT TO EACH ROD OVER THAT PORTION SURROUNDING EACH OF SAID RODS CAUSING THE STRAW TO PLEAT BETWEEN THE ENDS OF THE RODS. 